Industrial Hemp (Cannabis sativa): Pollen, Pollinators and Seed Germination

Industrial hemp (Cannabis sativa), has recently gained greater importance because it is a multipurpose crop that can be grown for fiber, grain and cannabidiol (CBD). Hemp does not produce nectar to attract pollinators, however, its prolific pollen production can make it an ecologically valuable crop to provide sustained nutritional options for bees during the cropping season. This study was carried out to evaluate the morphology of anthers, sugar content, and seed size, shape and germination of four hemp cultivars (CFX-2, Joey, Canda and Henola). Microscopic analysis revealed that anthers of each cultivar have five pollen sacs, which vary in length with Henola having the longest (4.82mm) and Joey the shortest (2.28mm). In addition, pollen grains lodged inside the pollen sacs varied in size from 0.10mm (Canda), 0.11mm (CFX-2), 0.13mm (Henola) and 0.17mm (Joey). Among the cultivars, Canda had the largest seed size (3.55mm) and Henola the smallest (2.80mm). Our findings indicate that sugar content of the anthers varied among cultivars with highest of 9.4% Brix in CFX-2 and lowest 7.1% Brix in Canda. Seed germination was highest on the second day for all varieties with 57.6%, 39.6%, 38%, and 36.4% for Canda, Joey, CFX-2, and Henola, respectively. Overall, after six days, Canda had highest (74.6%) seed germinated and Henola the least (53%). These findings will help growers understand variation among industrial hemp varieties and their implication for use in a cropping system.